The fish vs. fish oil smackdown

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  1. enliteneer’s avatar

    Great article as per usual!
    I would also add that any fat soluble supplement (fish oils, vitamin e, etc) should not be taken with fiber.   A wild speculation, but perhaps one possible reason for the lower absorption in the supplement takers, is that they were also supplementing with fiber.
    Also, there is a least one study suggesting that supplementing via capsule form, is not as effective as supplementing via liquid:
    Finally, wouldn’t the presumed lack of mercury /pcb in the distilled supplements be another consideration when choosing?  I recommend brands that has been independently certified by IFOS for purity:

  2. Chris Kresser’s avatar

    I agree that fiber should probably be avoided with fish oil.  I don’t recommend fiber supplementation in general.

    It makes perfect sense that liquids are absorbed better than capsules.  One less step for the body to go through to assimilate the oil.  But many people won’t take liquid fish oil.

    The last post in the series will cover how to choose a fish oil, including the toxins issue.

    Thanks for your comment!

  3. Elizabeth’s avatar

    This is a good series for readers needing the latest information on Omega 3. One study I read shows cod liver oil isn’t recommended because vitamin A interferes with the absorption of the vitamin D.

    I hope your next post in the series mentions Krill oil. Some nutrionists consider it superior to other fish oil. I can use Krill oil but other fish oil supplements give me nausea, even taken after a meal.

    I’m not fond of fish, so I try to eat it once a week and also take the Krill oil daily.

  4. Chris Kresser’s avatar

    Vitamin A does compete somewhat with absorption of D, but vitamin A is also an important co-factor that stimulates the vitamin D receptor.  The study you referred to showed a correlation between higher amounts of A and decreased protection from D, but did not show causation.  It had several other flaws.  In situations like this, I believe it’s best to go with the evolutionary wisdom of our ancestors, who thrived on foods like organ meats that are naturally high in both A & D.

    I am still uncertain about krill oil myself, so I don’t know how much I have to add to the debate.  There are very few studies supporting its use, and the few studies that do were sponsored by the company that manufactures the krill oil.  I did find one independent study that suggests it is effective, and there are many positive anecdotal reports like yours.  So I’d say it’s probably just fine.  I just wish there were more studies.

  5. Shameer’s avatar

    Hi Chris, excellent blog & articles.  I currentlyordered Green Pastures Fermented Cod Liver Oil.  Have you heard of this product? If so, what is your opinion the quality of this product?

  6. Chris Kresser’s avatar


    Thanks for your feedback! GP FCLO is #1 on my list of product recommendations. The next and final article in this series will be called “The Definitive Guide to Fish Oil”, so stay tuned!

  7. Jacob’s avatar

    Thank you so much for your informative articles! with all the confusion out there you are doing an exellent job to get to the heart of the matter and sort it all out for us.

    I would like to know your opinion on fish roe, is it better than fish? If yes  witch particular fish roe are the best? Thanks in advance.    

  8. Christian W’s avatar

    Hi Chris,

    That’s another excellent article! Especially the discussion about absorption was an eye opener.

    This is about some additional aspects that I’ve been thinking about:

    Some practitioners (e.g., Poliquin and Robb Wolf) recommend a very high intake (such as 0.5 – 1g /EPA, DHA per 10 pounds of body-weight/day) initially in a person transitioning from SAD to an ancestral diet.

    As far as I understand things (I may have got it wrong here and I don’t want to put words in other peoples’ mouths) the rationale has to do with counteracting the inflammatory effects of “legacy” omega 6 present throughout the body, especially if the person is losing weight. (There is also a spectrum of issues related to the metabolic syndrome that fish oil remedies.)

    The practice doesn’t seem to have a large basis in formal scientific studies, but is rather an idea that has been derived from successful clinical applications. People in the transitional stages are generally reported to do very well on higher amounts of fish oil and without any negative side effects. (Though I suspect that in some people high doses aren’t that well tolerated because of gut issues.)

    Poliquin has also mentioned fish oil supplementation as a therapeutic tool that helps kick start a person’s gradual behavioral change into better eating patterns. Fish oil, as it is providing essential brain nutrients, rapidly impacts patients’ mood in a positive manner and thus makes it psychologically easier for them to move forward with further changes in a positive direction. (This vs. immediately prescribing an over-night changes in diet).

    Perhaps you have any comments on these aspects of fish oil supplementation.

  9. Chris Kresser’s avatar

    Wild salmon roe is probably the #1 choice for obtaining DHA. Unfortunately, it’s incredibly expensive. To get a therapeutic dose of DHA, it would cost something like $27/day.

  10. Chris Kresser’s avatar

    Hi Christian,

    I like Robb’s podcast and he seems like a pretty knowledgeable guy.  However, I do have a problem with his recommendation of 1g of EPA/DHA per 10 pounds of body weight, for a couple of reasons.

    First, as you know, n-3 LCFA is highly unsaturated.  Any FAs that are highly unsaturated are susceptible to oxidative damage – regardless of whether they are n-6 or n-3.  Consuming 20g/d of fish oil could lead to a potentially dramatic increase in oxidative damage.  Our ancestors likely never ate more than 3-4% of calories as PUFA, and drinking 20g/d of fish oil is going to exceed that ratio by a mile.

    I understand that he’s not suggesting such a high intake over the long-term, and I get that the point is to push out the n-6 in the tissues and replace it with n-3.  It is true that it can take up to 6 months to shift the fatty acid profile in tissue.  However, I think significantly reducing n-6 intake and moderately increasing n-3 intake (to a maximum of 1.5 – 2g/d) is a more balanced approach that will decrease inflammation but also protect against oxidative damage.

    The other problem I have with that recommendation is that, as far as I’ve heard, Rob never tells people they need to be careful about what fish oil they choose, nor does he tell them how to choose it.  I’m writing an article all about that now that will be published in a couple of days.  Not all fish oils are created alike, and many of them are oxidized and/or made with poor quality ingredients.

    I’m concerned that people hear Robb’s advice and just go down to the store and buy the cheapest fish oil they can find (which I can certainly understand, if they’re going to be taking 20g/d of the stuff!)  Then they’re consuming huge amounts of rancid, oxidized fats and possibly significant amounts of PCBs, dioxins and heavy metals without realizing it.

    Poliquin has a good point and I don’t see a problem with using fish oil in that way, but I don’t see why 1.5-2g of a high quality, highly bioavailable product isn’t enough to produce the desired effect.

    What I’ve seen in several studies is that there’s a diminishing return at doses above 3g/d.  In other words, more is not necessarily better – especially considering the potential for oxidative damage.

    I’m keeping an open mind about this but these are my thoughts.

  11. Christian W’s avatar

    Hi Chris,
    Just wanted to thank you for the feedback on my question.
    Also the fish oil guide is excellent, as is the recent post about why we should eat fish.
    It’s hard to keep up with you! You are so incredibly productive.

  12. Chris Kresser’s avatar

    You’re very welcome.  I’m using this short period of time in between graduation and the licensing exam to get as much research and work done on my blog as I can. Once I get my license and start private practice, I’ll have a lot less time to put into this.

  13. Preston’s avatar

    Great post and excellent blog from what I’ve read so far Chris.
    Just wanted to add that the whole ‘dosage by consensus’ or from ‘anecdotal experience’ with regard to fish oil in new trainees has problems.  We have to remember that most of these people coming from a sedentary, SAD-eating lifestyle into a healthier diet and smart training (which they can definitely get from people like Poliquin, Wolf, and others) are going to see rapid improvements and likely lots of weight loss and reduction in inflammation from their new changes.  It is tempting to attribute this success to the supplements they take while doing this.  But it may be true that they see improvement in SPITE of taking high dose fish oil, not BECAUSE of it.  There are so many confounding factors that can contribute to their good results that it seems impossible to attribute the success to fish oil or any other supp.
    Until we see a solid body of well-designed, peer-reviewed randomized clinical trials looking at high fish oil dosage and some health markers, I prefer to remain skeptical and err on the side of caution- keeping supplement dosages low-to-moderate (no more than 3g of high quality EPA/DHA per day) and emphasizing food sources for these important oils along with elimination of excess N-6 intake.

  14. Chris Kresser’s avatar

    I couldn’t agree more, Preston. I’ve written elsewhere that I think giving 20g/d of fish oil is downright dangerous. The increase in oxidative stress could easily outweigh any potential anti-inflammatory benefits – especially because oxidative stress itself causes inflammation.

    Your point about confounding factors is spot on. A lot of people I know use this type of reasoning to support a vegan or vegetarian diet. They say how much better they felt going from the SAD to the vegan diet. Conclusion: vegan diet is healthy. Um, no. The majority of the improvement there is much more likely to come from what was removed (stopping the SAD) then what was added (tofu, brown rice, veggies).

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